pH colour indicator for use with agricultural compounds

ABSTRACT

This invention discloses a new class of pH indicators suitable for use in agricultural compounds. The class comprises naturally occurring substances which are extracts from grape skins, cabbage and lecithin. Safety concerns are now causing regulatory bodies to prohibit use of chemical pH indicators in compounds which are used for crops and animals. The naturally occurring compounds of this invention satisfy these concerns of the regulators and function as well as chemical indicators of the prior art.

This invention relates to agricultural compounds and more particularly to an improved agricultural compound which uses a naturally occurring pH indicator rather than a chemical pH indicator.

DESCRIPTION OF THE PRIOR ART

U.S. Pat. No. 5,278,132 granted to Gouws & Scheepers (Proprietary) Limited discloses a concentrate for dilution with water useful in the production of agricultural compounds for application to crops, soil or animals. The concentrate is added to the agricultural compound and then diluted with water until the desired pH is reached. This desired level of pH is controlled by the agricultural compound.

The patent discloses several chemicals which are used to determine the level of pH. These compounds include methyl red, resorcin blue, 2,5-dinitrophenol and chlorophenol red. These pH indicators change colour when the pH is changed and accordingly, provide a visual indicator as to when the desired pH is reached.

However, regulatory authorities throughout the world are now discouraging the use of non-natural ingredients especially when the agricultural compounds are used on crops and for treatment of animals. As a result, the chemical pH indicators currently in use are being rejected by regulatory authorities.

The Food and Drug Agency of the United States government sets out specifications of products which are approved for such use. These specifications are contained in, inter alia, Federal regulations, Title 21, Part 73.170. It is noted that methyl red is not listed and is therefore not an approved product.

Similarly, the European Economic Commission has also issued directives as contained in the EEC Additives No. E163 (Commission directive 95/45/EC as amended) which lists approved products for such use.

BRIEF DESCRIPTION OF THE INVENTION

Accordingly, the present invention provides an improvement wherein a completely naturally occurring product is used as the pH indicator.

To this end, in one of its aspects, the invention provides a naturally occurring pH indicator for use in a concentrate for preparing an agricultural compound which comprises an extract from grapes, cabbage or lichen.

In another of its aspects, the invention provides a concentrate comprising a mixture of a pH modifying agent and a naturally occurring pH indicator for colouring water, which concentrate can be diluted with water and added to an agricultural chemical for application to crops, soil or animals, the agricultural chemical having an activity that varies with the pH of the water and having an acceptable agricultural activity at a pH within the range of 4-6, wherein the proportions of pH modifying agent and pH indicator in the concentrate are such that when the concentrate is diluted with water and the pH of the water is modified by the pH modifying agent, the pH indicator indicates visually when the pH of the water is in the range of from about 4 to about 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The inventors have discovered that several naturally occurring products may be used as the colour/pH indicator in the concentrate as disclosed in U.S. Pat. No. 5,278,132. These naturally occurring compounds produce the same colour changes as do the chemical compounds but are acceptable to regulatory authorities throughout the world. These compounds exhibit no untoward activity to plants or animals.

The pH indictor of the present invention is selected from the group consisting of extracts from grape skins, cabbage or lichen. Extracts of grape skins are preferred because the required concentration is less but extracts of cabbage and lichen are also acceptable although they do require a higher concentration.

It is desired that the pH indicator change colour at a pH from about 4 to about 6. It is also desired that the indicator not have any deleterious effects on the crops or animals and it is for this reason that the naturally occurring products of the invention are so useful.

The grapes are first processed to remove the juice from the grapes to produce grape juice or wine and then the skin of the grape is removed. The grape skin extract is a purplish-red liquid which is prepared by the aqueous extraction of the fresh deseeded marc remaining after the grapes have been pressed. The extract contains anthocyanins, tartaric acid, tannins, sugars and minerals but not in the same proportions as in the grape juice. During the steeping process, sulphur dioxide is added and most of the extracted sugars are fermented to alcohol. The extract is then concentrated by vacuum evaporation during which almost all of the alcohol is removed. A small amount of sulphur dioxide may be present.

The extract shows a blue colour at a pH greater than 5 and a red colour at a pH lower than 5.

This extract was tested in the formulations disclosed in U.S. Pat. No. 5,278,132 and excellent results were obtained. However, it was found that much higher concentrations were required to show the visual colour change. Concentrations in the range of 10 to 25% were necessary to show the colour changes.

The experiments were repeated using cabbage extract and lichen extract. These worked although higher concentrations were necessary. Thus, while they clearly fall within the scope of this invention, the preferred product is grape extract.

An example of the concentrate (acid adjuvant) suitable for pH reduction, control and buffering in aqueous agricultural compositions for application to plants or soil an alkali sensitive agricultural chemicals subject to degradation in alkaline environments was formulated with the following composition: Nonyl phenoxy polyoxyethylene glycol 10.4 Monoortho-phosphoric esters 43.6 Diorthophosphoric esters 2.9 Isopropyl alcohol 15.6 Water 17.5 Grape skin extract 10.0 All percentages are expressed in mass/mass.

A second example of the concentrate (acid adjuvant) suitable for pH reduction, control and buffering in aqueous agricultural compositions for application to plants or soil an alkali sensitive agricultural chemicals subject to degradation in alkaline environments was formulated with the following composition: Nonyl phenoxy polyoxyethylene glycol 10.4 Monoortho-phosphoric esters 43.6 Diorthophosphoric esters 2.9 Isopropyl alcohol 15.6 Cabbage Extract 27.5 All percentages are expressed in mass/mass.

A third example of the concentrate (acid adjuvant) suitable for pH reduction, control and buffering in aqueous agricultural compositions for application to plants or soil an alkali sensitive agricultural chemicals subject to degradation in alkaline environments was formulated with the following composition: Nonyl phenoxy polyoxyethylene glycol 10.4 Monoortho-phosphoric esters 43.6 Diorthophosphoric esters 2.9 Isopropyl alcohol 15.6 Lichen extract 27.5 All percentages are expressed in mass/mass.

Accordingly, the use of a naturally occurring pH indicator represents a significant advance.

Although the invention describes and illustrates a preferred embodiment of the invention, kit is understood that it is no so restricted and includes in its scope, variations thereof. 

1. A naturally occurring pH indicator for use in a concentrate for preparing an agricultural compound which comprises an extract from grapes, cabbage or lichen.
 2. A concentrate comprising a mixture of a pH modifying agent and a naturally occurring pH indicator for colouring water, which concentrate can be diluted with water and added to an agricultural chemical for application to crops, soil or animals, the agricultural chemical having an activity that varies with the pH of the water and having an acceptable agricultural activity at a pH within the range of 4-6, wherein the proportions of pH modifying agent and pH indicator in the concentrate are such that when the concentrate is diluted with water and the pH of the water is modified by the pH modifying agent, the pH indicator indicates visually when the pH of the water is in the range of from about 4 to about
 6. 3. A concentrate as claimed in claim 2 wherein said pH indicator is selected from the group comprising extracts of grape skins, cabbage and lecithin.
 4. A concentrate as claimed in claim 3 wherein said pH indicator is an extract of grape skin.
 5. A concentrate as claimed in claim 4 wherein said pH indicator is present in a concentration of about 10 to about 25%. 